SPID#: 26 This study is directed toward the development of field-applicable antigen detecting assays. Rhesus monkeys, experimentally infected with Schistosoma mansoni, will be used to provide a controlled source of infection-related materials such as urine, feces and blood. Such material will be used to identify schistosome-specific antigens. Once identified, these antigens will be used to develop specific diagnostic tests. To date, five rhesus macaques have been infected with 300 S. mansoni cercaria. Samples of blood, urine and feces were collected bimonthly from the infected animals for 60 weeks, and the animals were treated with Droncit. Samples have continued to be collected following treatment. Both immunological and biological analyses of the collected samples are currently in progress. In addition to studies with experimentally infected rhesus macaques, three related studies in humans have been initiated during the past year. One study, designed to determine the transmission potential and risk for acquiring schistosomiasis in Lake Malawi, involved a cross-sectional survey of residents and visitors to Malawi. Evidence of current or past schistosome infection was found in one third of the study population. It was subsequently determined that recreational water contact at popular resorts on Lake Malawi was the most likely source of infection. In a second study, an island-wide serosurvey for schistosomiasis in Puerto Rico was initiated. Objectives are to determine the seroprevalence rate, status of transmission on the island and to evaluate the feasibility of controlling or eliminating this disease from Puerto Rico. Preliminary data indicate that schistosomiasis has been transmitted in a focal fashion during the past 20 years. Lastly, a longitudinal study is underway in which travelers recreationally exposed to schistosomiasis will be monitored, both before and after treatment. Efforts will be made to differentiate between treatment success and failure by following the immunological changes.